Colorectal cancer (CRC) is the most common tumor and the second leading cause of death in the Western world. The decrease in incidence and mortality by CRC in the population undergoing screening has been observed. Colonoscopy is the recommended method for detecting tumors in early stages, as well as identifying and resecting adenomatous polyps, which are the precursor lesions of most CRCs. Colonoscopy should be of high quality to decrease incidence and mortality by CRC and avoid interval cancer. The literature shows that colonoscopy does not prevent right colon lesions in the same way as the left colon lesions, with most of the interval cancers located in the right colon. Studies published so far show an increase in the adenomas detection rate (ADT) in the right colon in the second visualization of this segment and an increase between 2 and 10% if this second examination is performed with the proximal retroflexion maneuver.Retroflexion is a safe maneuver in expert endoscopists. The aim of our study is to evaluate the ADT in the right colon by means of a second visualization by performing proximal retroflexion or second frontal visualization at random in the CCR screening population.

Inclusion Criteria:

• Subjects participating in the Colorectal cancer Screening program with faecal immunological test > 100ng / ml.
• Ages between 50-69 years.
• Adequate preparation according to the Boston scale: in right colon (score> 2 in this section)
• Informed consent.

Exclusion Criteria:

• Refusal to give informed consent.
• Subjects with elevated colorectal cancer risk due to family history or inherited diseases of polyposis or inflammatory bowel disease
• Symptomatic subjects.
• Diverticulitis, inflammatory bowel disease or colonic stenosis during the exploration
• Inadequate preparation according to Boston cleanliness scale (score ≤ 2 in right colon)